WASHINGTON (CNN) -- A scaled-back, modern U.S. military would cut the Army to its pre-World War II size and do away with the A-10 "Warthog" attack jet, Defense Secretary Chuck Hagel said on Monday in proposing a new budget to reflect the end of America's longest war.
"After Iraq and Afghanistan, we are no longer sizing the military to conduct long and large stability operations," Hagel said in announcing his 2015 Defense Department budget plan.
Downsizing due to modernization and budget constraints began under Hagel's predecessor, Robert Gates, and the proposal outlined on Monday described a new phase of change.
"As we end our combat mission in Afghanistan, this will be the first budget to fully reflect the transition DoD is making after 13 years of war -- the longest conflict in our nation's history," Hagel told reporters at the Pentagon.
The former Republican senator from Nebraska describes a military capable of fighting on one war front and maintaining effective defenses for a second while shifting to a more tactical capability.
"Our analysis showed that this force would be capable of decisively defeating aggression in one major combat theater -- as it must be -- while also defending the homeland and supporting air and naval forces engaged in another theater against an adversary," he said.
The Pentagon budget for the current fiscal year is just shy of $500 billion, a spending figure reached through congressional compromise.
Hagel acknowledges the changes mean assuming more risk, but said the military would better situated to respond to the evolving security challenges facing the country.
"We must maintain our technological edge over potential adversaries," he said, adding that "the military must be ready and capable to respond quickly to all contingencies and decisively defeat any opponent should deterrence fail."
The recommendations in the budget plan for 2015 and ensuing years "favor a smaller and more capable force -- putting a premium on rapidly deployable, self-sustaining platforms that can defeat more technologically advanced adversaries," Hagel said, adding that they also include "important investments to preserve a safe, secure, reliable, and effective nuclear force."
In the proposal, Hagel calls for cutting the Army to a level of 440,000 to 450,000 troops, which would be the lowest level in more than 70 years. At its height, the Army had 570,000 troops after the September 11,2001, terrorist attacks.
According to Hagel, the budget proposal protects funding for cyberwarfare and special operations, and preserves funding for the controversial and costly F-35 fighter jet.
His plan would retire the A-10, which Hagel called a 40-year-old, single-purpose aircraft designed for Cold War operations, at a cost savings of $3.5 billion over five years.
Separately, Hagel said 900 additional Marines would be assigned to bolster security at U.S. embassies around the world under his proposal. Diplomatic security has received close scrutiny since the deadly terror attack on the U.S. consulate in Benghazi, Libya, in 2012.
Hagel's budget will be formally proposed to Congress next week and is expected to come under sharp criticism from legislators, especially those with big military bases or a heavy presence of contractors in their districts or states.
Republican hawks have battled the military force reductions that are part of Obama's attempts to reduce defense spending as part of overall deficit reduction.
Hagel warned that if Congress fails to eliminate planned across-the-board spending cuts in future years, the military reductions would be on a greater scale.
Some of those forced cuts, known as sequestration, were eased for this year and next under the budget deal worked out by Congress in December.
CNN's Halimah Abdullah contributed to this report.
™ & © 2014 Cable News Network, Inc., a Time Warner Company. All rights reserved.